Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
The invention is herein described with particular reference to compositions for cleaning medical instruments, but is not limited to that use. As herein used the term “medical instruments” is intended broadly to include surgical instruments such as scalpels, biopsy instruments, clamps, and the like; endoscopes, colonoscopes, laparoscopes and other paraphernalia used for surgical investigation or intervention; and other instruments used in the practice of medicine, surgery, and dentistry which require cleaning, disinfection or sterilisation. The term is also intended to include instruments having similar cleaning requirements such as those used in hairdressing, cosmetic treatments, tattooing, body piercing etc as well as other applications where removal of human/animal sebum and/or body secretion is required. Many medical instruments are made from or incorporate a variety of construction materials and cleaning compositions must be such as not to attack any such materials.
It is common practice to clean medical instruments after use with one patient and prior to treatment of another by scrubbing to remove blood, tissue, loose proteinatious and other soils, and then soaking for a predetermined period in an enzyme preparation adapted to further digest or loosen any proteinacious materials remaining on the instrument surface. The instruments are then rinsed clean and subjected to further disinfection or sterilization procedures. To minimize the possibility of cross infection instruments used with one patient are desirably cleaned separately from those used with another.
Preparations for use in cleaning medical instruments consist generally of a concentrate comprising one or more surfactants in combination with one or more proteolytic enzymes. The concentrate is diluted to a working strength (normally a hundredfold dilution) prior to use. One such formulation has been described by NOVO NORDISK (“Novo-formulation”). Three preparations used internationally for this purpose are EPIZYME® (a product of 3M), MEDIZYME® (a product of Whiteley Industries Pty Ltd., Sydney Australia) and ENDOZYME® (a product of Ruholf Corporation, N.Y., USA). While such products are generally effective and widely used there remains a need for products which are more efficient, and especially for preparations which are capable of achieving a predetermined level of effectiveness within a shorter time than those currently available.
The concentrate must be sufficiently stable in transit and storage prior to use to satisfy the needs of commerce. The choice of surfactants which in practice can be formulated in concentrated aqueous solutions is limited. Either the surfactants limit the storage stability of the concentrate, resulting in problems of foaming on dilution, provide insufficient reduction in surface tension, destabilize other components of the system such as enzymes, or suffer from other disadvantages. Mostly, formulators utilize surfactants chosen from a small group of conventional and well known nonionic surfactants which have been found to be satisfactory for such uses, but there remains an unsatisfied demand for formulations of improved efficiency.
It is an object of the invention to provide an improved surfactant system, and of preferred embodiments of the invention to provide an enzyme based cleaning composition which avoids problems of the prior art and/or provides improved performance.